Patent GB-398861-A (GB)
Title: Improvements in or relating to variable speed gearing and like or associated mechanism for the transmission of power
IPC: F16D67/00
Filed: 1931-12-19
Abstract: 398,861. Hydro-mechanical variablespeed gearing. SWAN, J. G., 14, Old Square, Lincoln's Inn, London. Dec. 19, 1931, Nos. 35193/31,2504/32, and 23344/32. [Class 80 (ii).] A transmission unit comprises an hydraulic coupling with one member fast on a driving- shaft, the other member fast or one-way mounted on a driven shaft, and a planetary train arranged in parallel so that braking an element thereof retards or stops, or drives, the driven shaft. In a form shown in Fig. 2, driving and driven shafts 51, 55 are fast to hydraulic members 52, 53, respectively, and a brake-drum 59 is connected by a sleeve to the carrier 57 of planets 58 which mesh with a sun gear 54 and with an annulus 56 rigid with these hydraulic members respectively. The application of a brake 60 to the drum 59 retards or reverses the shaft 55. When the drum 59 is held fast, the member 53 spins backwards and reduces the flow of liquid in the coupling. This unit may be used upon a vehicle in series with mechanical change-speed gearing of any type, not described or shown, preferably with a one-way clutch between the annulus 56 and the shaft 55. The application of the brake facilitates speed changing in the mechanical change gearing. Specifications 353,108, 353,109, 353,334, 361,281, 366,081, and 391,837 are referred to in this connection. A cam device is described for opening the engine throttle as the brake 60 is applied to prevent engine stoppage Ducts 73, 75 serve to communicate oil between the chamber containing the planetary train and the inner toric space 74 of the coupling, and there is a spring- pressed seal valve at 76. Specification 375,534, [Group XXIX], is referred to in this connection. In Fig. 3 (not shown), an additional planetary train is provided to the end that stoppage of the brake drum will effect a slow reversed drive of the driven shaft of the unit. An arrangement described with reference to Fig. 4 (not shown), has two planetary trains and two drums. If neither drum is braked, the hydraulic coupling acts as such. If one drum is held, the two trains are operative to drive the driven shaft of the unit slowly in reversed direction. If the other drum alone is held, one train is operative to drive the driven shaft forwardly at reduced speed with additional torque. In the arrangement shown in Fig. 1, there are stepped planet gears 18, 19 carried by the driving hydraulic member 12. A one-way clutch 24 is between the brake drum 22 and the driven shaft 16 so that restraint applied to the former is transmitted through the clutch 24 to the latter. The driven hydraulic member 13 is fast on a middle shaft 20 with a forwarddriving one-way clutch 21 connecting to the shaft 16. The planets 18, 19 mesh respectively with a sun gear 15 fast on the shaft 20 and with a larger sun gear 17 fast on a sleeve 23 of the drum 22. When the drum 22 is held fast, the torque in the coupling is eliminated simultaneously with the holding fast of the shaft 16. The ratio of the gear train is such that the backward spin given to the member 13 by the planetary train introduces centrifugal force which stops the oil circulation in the coupling. In an arrangement shown in Fig. 6, the planetary train 215, 218, 219, 217 becomes operative to drive the driven shaft 216 of the unit forwardly when a drum 222 is held so as to prevent the sun gear 217 from turning backwards. An interposed free-wheel clutch 229 is of the appropriate sense. The planets are carried on the driving member 212 of the coupling fast on the driving-shaft 210. The driven hydraulic member 213 is fast on the driven shaft 216 with the sun gear 215. A reservoir 220 is connected by ducts 226, 227 to the inner toric space 228 of the coupling. Specification 385,086, [Group XXIX], is referred to in connection with Fig. 6.